Billionaire Facebook CEO Mark Zuckerberg and his physician wife are expecting a baby girl, the happy couple announced — where else? — on Facebook.

And the baby has already given a thumbs up “like” with her hand in an ultrasound, the over-the-moon Internet entrepreneur bragged.

“Priscilla and I have some exciting news: we’re expecting a baby girl,” Zuckerberg posted Friday from Palo Alto, CA.

“This will be a new chapter in our lives,” Zuckerberg said of himself and Priscilla Chan, his wife of three years, who he said has suffered three miscarriages during their efforts to have a child.

“We’ve been already been so fortunate for the opportunity to touch people’s lives around the world — Cilla as a doctor and educator, and me through this community and philanthropy. Now we’ll focus on making the world a better place for our child and the next generation,” Zuckerberg wrote.

The couple has been trying to have a baby for “a couple of years,” the 31-year-old CEO wrote. Chan’s miscarriages were “a lonely experience” that the couple was at first unwilling to burden friends with.

“So you struggle on your own,” he said. Then, “when we started talking to our friends, we realized how frequently this happened — that many people we knew had similar issues and that nearly all had healthy children after all.”

“Our good news is that our pregnancy is now far enough along that the risk of loss is very low and we are very hopeful,” he said, without revealing a due date.

“Cilla and our child are both healthy, I’m extremely excited to meet her and our dog Beast has no idea what’s coming. In our ultrasound, she even gave me a thumbs up “like” with her hand, so I’m already convinced she takes after me,” he wrote.

“We’re looking forward to welcoming her into the world and sharing more soon when she’s ready to come out and meet everyone!”